The present invention relates to omnidirectional antennas, particularly a stacked biconical antenna.
Biconical antennas have commonly been used for their omnidirectional characteristics in azimuth. It has been found that given a desired gain, the volume for a biconical antenna can be reduced by replacing a single biconical with a stacked array of a plurality of biconical antennas. Several examples of stacked biconical antennas are discussed below.
U.S. Pat. No. 2,532,551 (Jarvis) discloses two stacked biconical antennas, one for transmitting and the other for receiving. The two biconical antennas are separated from one another by a separation pipe. Each antenna has its own cable separately fed to it through the axis of the antenna.
U.S. Pat. No. 2,726,388 (Kandoian) discusses the existence of stacked biconical radiators and the arrangement of transmission leads and wave guides by spiralling them around the stacked array. Kandoian et al. expressed their reservations regarding the shortcomings of such a system. Kandoian et al. discloses instead the arrangement of transmission lines through the axis of the stacked antennas.
U.S. Pat. No. 2,711,533 (Litchford) discloses a stack of three biconical antennas in which the biconical sections are supported by metallic members. Litchford recommends that the radiating elements in each of the biconical sections be excited in phase to ensure that their horizontal radiations from each section are additive.
U.S. Pat. No. 3,795,914 (Pickles) discloses a stack of biconical antennas in which a styrofoam support encircles the periphery of the stacked antennas. Absorbing wires are arranged about the antennas and the styrofoam supports to improve absorption of reflected energy. An outer radome encircles the stack of biconical antennas which are rotatable within the radome.